Memory is one type of integrated circuitry, and is used in computer systems for storing data. Memory may be fabricated in one or more arrays of individual memory cells. Memory cells may be written to, or read from, using digit lines (which may also be referred to as bit lines, data lines, or sense lines) and access lines (which may also be referred to as word lines). The digit lines may electrically interconnect memory cells along columns of the array, and the access lines may electrically interconnect memory cells along rows of the array. Each memory cell may be uniquely addressed through the combination of a digit line and an access line.
Memory cells may be volatile, semivolatile, or nonvolatile. Nonvolatile memory cells can store data for extended periods of time, in many instances including when the computer is turned off. Volatile memory dissipates and therefore requires being refreshed/rewritten, in many instances multiple times per second. Regardless, memory cells are configured to retain or store memory in at least two different selectable states. In a binary system, the states are considered as either a “0” or a “1”. In other systems, at least some individual memory cells may be configured to store more than two levels or states of information.
Example volatile memory cells are dynamic random access memory (DRAM) cells. A DRAM unit cell may comprise a transistor coupled with a charge-storage device, such as a capacitor. Other example memory cells may lack capacitors, and instead may utilize electrically floating transistor bodies. Memory which utilizes electrically floating transistor bodies to store data may be referred to as zero-capacitor-one-transistor (0C1T) memory, as capacitor-less memory, or as ZRAM™ (zero capacitance DRAM), and may be formed to much higher levels of integration than DRAM.
One type of component that may be used in memory and other integrated circuitry is a transistor. Such may be oriented vertically, horizontally, a combination of vertically and horizontally, diagonally, or otherwise. Transistor orientation refers to the general direction of current flow through the transistor channel between a pair of source/drains of the transistor. In this document, vertical is a direction generally orthogonal to a primary surface relative to which a substrate is processed during fabrication and which may be considered to define a generally horizontal direction.